Latest research shows that yawning helps in keeping the brain cool, contradicting the popular belief that yawning promotes sleep and is a sign of tiredness.

• 最新研究表明，打呵欠有助于保持头脑清醒，与“打呵欠促使人进入睡眠状态以及是疲倦的一种表现”的普遍看法正好相反。